Solar concentrators employ reflectors, lenses, or a combination thereof to concentrate incident light on a receiver. The resulting irradiance pattern projected onto the receiver is generally fairly non-uniform. The intensity in the central region of the receiver is generally much greater than the intensity at the periphery. This intensity variation can significantly impact the collection efficiency where the receiver consists of photovoltaic cells. Some concentrators use a secondary reflector to homogenize the light from the primary reflector. Although the secondary can improve the uniformity of the pattern of light on the receiver cells, some non-uniformity generally persists and the additional reflections in the secondary generally result in some inadvertent absorption of light. Additional loss of incident light may result from tracking errors that occur while the concentrator attempts to locate the sun or re-locate the sun after it reemerges from behind cloud cover, for example. There is therefore a need for a tracking concentrator that can compensate for non-uniform irradiance patterns, minimize losses due to tracking errors, and minimize losses do to target acquisition or re-acquisition.